1. Field of the Invention
This invention relates to a network pattern reducing apparatus for reducing network patterns caused by a fiber bundle in an endoscope image transmitted by an image guide made of the above mentioned fiber bundle.
2. Description of the Related Art
Recently, there has been extensively utilized an endoscope whereby organs within a body cavity can be observed by inserting an elongate insertable section into the body cavity or, as required, various therapeutic treatments can be made by using a treating instrument inserted through a treating instrument channel. In the above mentioned endoscope, there is a fiber scope wherein an object image formed by an objective lens in the tip part of the insertable section is transmitted to an eyepiece section by an image guide made of a fiber bundle so as to be observable with a naked eye. Also, with a television camera connected to the eyepiece section of the above mentioned fiber scope, the above mentioned object image is imaged so as to be able to be displayed in a monitor.
The fiber bundle forming the above mentioned image guide is made by closely bundling several tens of thousands of fine optical fibers forming respective pixels. The above mentioned optical fiber consists of a center core and a clad on its outer periphery. A fiber bundle made by bundling such optical fibers consists of sections transmitting the optical information of the object through the above mentioned cores and sections consisting of clearances between the above mentioned clads and respective optical fibers, and not transmitting the optical information of the object.
Therefore, network patterns by the sections not transmitting the above mentioned optical information will appear in the image transmitted by the image guide made of this fiber bundle. There is a problem that such network patterns not only will contribute nothing to the information of the object but also will make the object image hard to see. Therefore, it is desirable to provide an optical low pass filter between the image guide and the imaging means to remove the network pattern components. However, there is a problem that, in such case, the resolution will be reduced by the optical low pass filter and, as a result, the picture quality will be deteriorated. There is also a problem that, when such optical low pass filter is provided, the operating section will become bulky, the weight will increase and the operation will become difficult.